$Λ$CDM as a Noether Symmetry in Cosmology

Abstract

The standard ΛCDM model of cosmology is formulated as a simple modified gravity coupled to a single scalar field ("darkon") possessing a non-trivial hidden nonlinear Noether symmetry. The main ingredient in the construction is the use of the formalism of non-Riemannian spacetime volumeelements. The associated Noether conserved current produces stress-energy tensor consisting of two additive parts -dynamically generated dark energy and dark matter components non-interacting among themselves. Noether symmetry breaking via an additional scalar "darkon" potential introduces naturally an interaction between dark energy and dark matter. The correspondence between the ΛCDM model and the present "darkon" Noether symmetry is exhibited up to linear order w.r.t. gravity-matter perturbations. By breaking the Noether symmetry we obtain H0 = 69.18±4.293 and σ8 = 0.7860 ± 0.1106 from combined data of the direct measurements of the Hubble expansion and growth of matter results, which is closer to latest PLANCK results.